On 06.09.2006 [14:34:53 -0700], Nishanth Aravamudan wrote:
> On 06.09.2006 [12:07:15 -0700], Nishanth Aravamudan wrote:
> > We currently skip over negative increments, but in a potentially
> > incorrect manner, as we still move our heap around. If both newsize and
> > increment are negative, then we check to see if we can free up at least
> > a full hugepage. We then unmap appropriately and move the top of the
> > heap around.
> >
> > Signed-off-by: Nishanth Aravamudan <[EMAIL PROTECTED]>
>
> Hrm, further testing is revealing some issues with this.
We currently skip over negative increments, but in a potentially
incorrect manner, as we still move our heap around. If both newsize and
increment are negative, then we check to see if we can free up at least
a full hugepage. We then unmap appropriately and move the top of the
heap around.
Signed-off-by: Nishanth Aravamudan <[EMAIL PROTECTED]>
---
Small problem found with original patch, fixed below.
diff -urpN a/morecore.c b/morecore.c
--- a/morecore.c 2006-09-06 14:48:20.000000000 -0700
+++ b/morecore.c 2006-09-06 14:44:43.000000000 -0700
@@ -101,6 +101,34 @@ static void *hugetlbfs_morecore(ptrdiff_
DEBUG("heapbase = %p, heaptop = %p, mapsize = %lx, newsize=%ld\n",
heapbase, heaptop, mapsize, newsize);
+ /* maybe need to shrink the heap, as we're giving back memory */
+ if ((newsize < 0) && (increment < 0)) {
+ newsize = labs(newsize);
+ if (newsize > blocksize) {
+ /* number of hugepages we can free from mapsize */
+ newsize = ALIGN(newsize - blocksize, blocksize);
+ /*
+ * free up hugepages at the appropriate
+ * boundary
+ */
+ munmap(heapbase + mapsize - newsize, newsize);
+ mapsize -= newsize;
+ }
+
+ /*
+ * need to do this in the reverse order for
+ * shrinking the heap
+ */
+ heaptop = heaptop + increment;
+ p = heaptop;
+ goto done;
+ }
+ /*
+ * if newsize < 0 && increment > 0 then the request fits into
+ * the currently mapped space, and we'll fall through to the
+ * return
+ */
+
/* growing the heap */
if (newsize > 0) {
/*
@@ -151,6 +179,7 @@ static void *hugetlbfs_morecore(ptrdiff_
/* and we now have added this much more space to the heap */
heaptop = heaptop + increment;
+done:
DEBUG("... = %p\n", p);
return p;
}
--
Nishanth Aravamudan <[EMAIL PROTECTED]>
IBM Linux Technology Center
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